Since the introduction of the original formaldehyde histofluorescence method 20 years ago, innovations in the fluorescence histochemical methodology has played a continuous and important role not only in the development of the monoamine research field but also as a key tool for unraveling the chemical anatomy of the nervous system. Based on developments and discoveries made during the last grant period we propose to continue our project along the following lines: (1) To work out a procedure, which combines our recently developed aluminum-oatalysed formal-dehyde (ALFA) method with serotonin immunocytochemistry, for optimum visualization of noradrenaline, dopamine and serotonin in consecultive sections from the same specimens. (2) Furthur studies on two prinoipally new reaction mechanisms, (discovered during the last grant period) for historchemical visualization of N acetylated indolamines (such as melatonin) and tertiary indolamines (such as bufotenin) in tissue. (3) Studies on the possbility to quantify monoamine fluorophores by HPLC technique in samples dissected from fluorescence histochemical sections. (4) Further studies on the organization of the central dompaminergic system, with special referecne to three previously unknown projecttions - to the temporal cortex, the lateral habernular nucleus and the spinal core - which were discovered during the last grant period. (5) Further studies on the embryonic and early postnatal development of the central oatecholamine systems using a new "ontogenetic" version ofa the ALFA method. (6) Studies on the possiility to replace severed monoaminergic and cholinergic connections in the adult rat using a new method for intracerebral grafting of dissociated neuronal cell suspensions. These experiments will primarily be carried out in rats subjected to lesions that mimio the condition in patients with Parkinson's disease, and Huntington's chorea.